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Biomedical subjects

I Karube

Publications and source records attributed to I Karube.

137 records · Page 8Linked to original sources
PubMed1976

Photocontrol of urease-collagen membrane activity.

(1) Urease (EC 3.5.1.5.) was modified with beta-1-[3,3-dimethyl-6'-nitrospiro-(indoline-2,2'-2H-benzopyrene)] propionic anhydride. Three amino acid residues of urease were modified by the anhydride at a molar ratio of 2000. (2) The activity of modified urease was decreased with ultraviolet irradiation and then restored to the initial activity with visible light irradiation. (3) Modified urease was used to prepare a urease-collagen membrane. The apparent Michaelis constant (Km) of the modified urease-collagen membrane ultraviolet light was identical to that of the membrane under visible light. (4) The optimum pH of the modified urease-collagen membrane was displaced toward lower pH values with ultraviolet irradiation. At higher ionic strength, the pH activity curve of the membrane was displaced toward higher pH values. (5) The thermostability of urease was increased with its modification.

Ammonium Sulfate↗
PubMedDate not supplied

Detection of toxic chemicals with high sensitivity by measuring the quantity of induced P450 mRNAs based on surface plasmon resonance.

In this study we describe a novel sensor system to detect toxic chemicals based on measurement of the quantity of Saccharomyces cerevisiae P450 mRNAs induced by them. Detection was conducted using a flow-injection-type sensor system based on surface plasmon resonance (SPR). The DNA and peptide nucleic acid (PNA) probes containing a complementary sequence to a part of P450 mRNA were immobilized on the sensor chip and the P450 mRNAs hybridized to the probes were quantified. We succeeded in detecting 10 ng/L (10 ppt) of atrazine using both DNA and PNA probes. Using this sensor system, we were able to detect bisphenol A in addition to atrazine. Furthermore, we achieved higher sensitivity by amplifying the target P450 mRNA based on nucleic acid sequence-based amplification (NASBA). This method allows for sensitive, rapid, and easy detection of some toxic chemicals.

Atrazine↗
PubMedDate not supplied

Miniaturized detectors for a chemical analysis system.

Recently, several studies about miniaturized chemical analysis systems fabricated with micromachining methods were reported. These systems have some advantages, such as fast response, small amount of sample, and low consumption of reagents, as compared with the conventional system. With such a small system, design of the detector units is very important to monitor analytical performance. This paper introduces some examples of micromachined detectors for miniaturized chemical analysis systems.

Catecholamines↗
PubMedDate not supplied

Micromachined detectors for an enzyme-based FIA.

Micromachining techniques were applied to construct biosensor systems. The micromachined biosensors have small size, low production cost, and good reproducibility. We made some detection units for flow injection analysis (FIA). An electrochemical flow cell was fabricated, and both the enzyme immobilized column and electrochemical detector were integrated onto the same chip. A chemiluminescence detector was also fabricated and applied to the determination of glucose and lactic acid contained in human serum and urine.

Biosensing Techniques↗
PubMedDate not supplied

Pulse immunoassay for human immunoglobulin G using antibody bound latex beads.

Pulse immunoassay was applied in the immunoassay of human immunoglobulin G (H-IgG). Antibodies to H-IgG were covalently immobilized on the surface of latex beads (1 microM). Immunoreaction of the antibody bound latex beads (Ab-L) and H-IgG was performed using electric pulses. Agglutination rate (AR), defined by the following equation, was used to estimate the immunoreaction rate (formula; see text) where Nn is the total number of beads forming n bead agglutinations. Each Nn was determined by analyzing photographs of the samples. When 140 microliter of Ab-L suspension (0.7%) containing H-IgG (6.7 X 10(-6) g ml-1) was reacted using electric pulses (peak height 2 kV cm-1, pulse width 20 microseconds, pulse frequency 8 kHz), AR increased sharply and reached 50% after 10 min. In contrast, when the same sample was reacted without electric pulses, AR increased very slowly and only reached 20% after 20 min. Therefore, the immunoreaction of H-IgG and Ab-L can be carried out more rapidly by applying electric pulses.

Agglutination↗